Epimers of bicyclo[2.2.2]octan-2-ol derivatives with antiprotozoal activity

(2SR,6RS,7RS)-4-Dialkylaminobicyclo[2.2.2]octan-2-ols and several of their esters have shown promising activity against the causative organisms for malaria and sleeping sickness. The base-catalyzed epimerization of the alcohols was carried out by different methods giving their (2RS,6RS,7RS)-isomers. Best results were obtained by the consecutive use of potassium tert-butoxide and sodium. The isomeric alcohols were converted to selected esters. All new compounds were tested for their activity against Trypanosoma brucei rhodesiense (STIB 900) and a multiresistant strain of Plasmodium falciparum. The antitrypanosomal activity and the cytotoxicity were in general increased. The most active antitrypanosomal agents were the benzoate 8b and the 4-chlorobenzoate 9b of the 4-pyrrolidino series. The nicotinate 10a and the isonicotinate 11a showed the highest antiplasmodial activities.